A representative, prospective population sample of 1,205 7-year-old children in a larger Finnish city was followed for 15 years for headache and other medical disorders and symptoms. The comorbidity associated with headache was found to be higher than expected. Allergy and bronchial asthma, diabetes mellitus and stomachache were more common in boys than in girls, while psychiatric symptoms and sleep disturbances were more typical of girls than boys. The prevalence rate of any headache and migraine increases up to the age of 13 years, but after that age, a decline in the prevalence is found in boys, while girls show an increasing trend both in the presence and in the frequency of any headache and migraine.